In animal studies, DMP 266 has been demonstrated to induce its own metabolism and increase hepatic CYP3A and CYP2B enzyme activities. In humans, CYP3A4 is the predominant phase-I metabolizing enzyme present in the liver and intestine, and the available data suggest that it may be induced by DMP 266. To definitively determine if this is the case, 24 healthy volunteers will be randomized to receive either DMP 266 (200 mg or 400 mg/daily) or placebo orally for 10 days. Intestinal biopsies will be obtained prior to the first dose of DMP 266 and on the day after administration of the 10th dose. In addition, single intravenous doses of [14-C-N-methyl] erhthromycin will be administered on 9 different occasions throughout the study.